Manufacture of multifilament rubber threads



Feb. 17, 1942. L. D. ALDRICH 2,273,032 I MANUFACTURE OF MULTIFILAMENT RUBBER THREADS Filed June 15, 1958 HER Patented Feb. 17, 1942 p 2,273,082 MANUFACTURE or MULTIFILA'MENT RUBBER THREADS Lucius Dexter Aldrich North Providence, R. 1,,

assignor, by mesne assignments, to United States Rubber Company, New York, N. Y., a

corporation of New Jersey Application June 15, 1938, Serial No. 213,762

16 Claims.' (Cl. 18-8) This invention relates to the manufacture of rubber threads and more particularly to methods and apparatus for the production of -multifilament rubber threads having a desired cross sectional configuration.

Various methods have been proposed for grouping or associating together a plurality of rubber threads in a tacky condition to form a continuous composite grouping of the individual filaments into a rubber tape or cord. One previous procedure for making rubber threads having a cross-section comprising an aggregate of circular configurations has been suggested in which a specially designed nozzle extrudes, substantially in contact with each other, a desired number of threads from rubber latex or a solution of rubber. The nozzle isso constructed that the individual filaments are extruded closely together, preferably converging toward a central axis, and are immediately caused'to adhere or coalesce together. upon emerging from the nozzle. This method obviously cannot be utilized for producing a generally flat thread in which the component filaments are-to be aligned in a substantially straight row. When arranging the filaments around a central axis by such a procedure, the grouping or relationship of the threads with respect to each other is fortuitous, and cannot be accurately controlled. In practicing this procedure, it is imperative that a specially designed nozzle be utilized.

In another previous method for the production of this type of thread, a plurality of: filaments are formed by depositing latex into rounded grooves around the periphery of heated wheels, and pressing the partially dried latex filaments into the desired arrangement by the use of cooperating flanged or grooved rollers. The pressure necessary in practicing this method deforms the rounded filaments into a rectangular block so that an almost unitary composite fiat-sided thread is the result.

It has also beensuggested to form a substantially fiat grooved rubber tape, such as golf ball p separate filaments, into a dehydrating and setting medium, allowing the filaments lightly to contact each other side'by side as they travel .by extruding rubber latex as a series of originally extruded, flattening them at least on the opposite sides.

In accordance with the multi-filament rubber thread, for example in the form of a cord or a tape, may readily be, produced without the application of suificient pressure at any time to alter the original crosssectional configuration of any individual filament of the ultimate multifilament thread. The

invention also provides for the accurate production of a multiple filament rubber thread in which the desired cross-sectional configuration or grouping of the filaments may be accurately predetermined and accomplished.

The accompanying drawing represents illus trative embodiments of the invention, in

Fig. 1 is a plan view, with a section removed, of one side of an apparatus for forming multifilament rubber threads;

Fig. g is a cross-sectional iew taken along the line 2-2 of Fig. 1;

cross-section are drawn within a fluid medium beneath and in contact with grouping means adapted to impart the desired grouping configuration'to the plurality of filaments. For example, if a substantially flat thread is desired, each group of filaments is drawn or floated within -a fiuid medium beneath and in contact with a through the medium, washing the tape temporarily formed by aggregation of the separate fil-' aments, and passing the tape between two cooperating rollers which by pressure consolidate the temporary group of filaments into a final flat grooved tape. Thepressure means employed in this method also deform the round filaments forming member having a substantially flat or slightly concave lower surface. If, .on the other hand, a thread of generally triangular cross section is desired, a forming or grouping member is employed in whichthe lower forming surface may correspond generally to the shape of an inverted V. Other grouping configurations of the filaments may be obtained by the use of grouping means or. forming members having a lower surface corresponding generally to the ultimate configuration of the particulanthread desired. From beneath the grouping member,

present invention a the multifilament thread initially produced thereby is preferably drawn over and in contact with a shape-retaining member having on its upper surface a configuration corresponding to that of the lower surface of the forming member, The shape-retaining member holds the component filaments of the composite thread in their propergrouping configuration so that they retain their shape and grouping arrangement permanently. It is also contemplated to provide adjustable shape-retaining means which in one position will retain the grouped individual filaments of a thread in a certain desired arrangement, and in another positionwill retain them in a different formation.

In carrying out the invention, a plurality of at I least partially coagulated rubber filaments may ments in their tacky or partially coagulated state I are then drawn through any suitable fluid medium, which may be the coagulant itself, or hot water in the case of a heat sensitive latex. or any desired fiuid of higher specific gravity than the partially coagulated rubber filaments. The grouping means for each group of filaments are preferably in the form of a bar -or rod. positioned within the fluid medium transversely to the diin generally triangular relationship beneath the.

rection of travel of the filaments as they emerge from the nozzles. As the filaments are drawn through the fiuid medium beneath the groupinc bar, they tend to float and since they are of lower specific gravity than the fiuid medium, they rise into contact with the grouping surface of the forming or grouping member. Before arrival under the grouping member, the filaments are preferably aligned vertically, as by means of a staggered row of pins or rods which may convenientlv project upwardly through the fluid medium. These vertical aligning means permit the desired number of filaments to be proximately. positioned into a group immediately prior to their formation into the composite thread. Each group of filaments is then drawn beneath the forming member.

The lower surface of the forming member is substantially horizontal and is preferably slightly concave when a substantially flat thread is desired. As the filamentsar impelled upwardly against this surface by reason of their buoyancy within the fiuid medium, they become associated into a substantially flat or slightly concave group, depending upon the degree of curvature of the lower surface of the member. By reason of their tacky or partially coagulated condition, each filament adheres to that or those adjacent to it, thus forming the composite thread, the individual filaments of which are aligned according to the shape of the lower surface of the grouping memher. This alignment is retained and adhesion is assisted by subsequent contact with the upper surface of the shape-retaining member. The pressure exerted by reason of the buoyancy of the filaments against the grouping member or their contact with the shape-retaining member is insuflicient to deform them, yet they retain their initial association with each other.

When a grouping or forming member having a generally triangular lower surface is employed, as for example when shaped like an inverted V, one of the filaments contacting against it will naturally assume a position closest to the apex, while the other two become horizontally aligned below and in contact with it. If the angle of the V approximates 60 or is of slightly greater angularity, all three filaments will be in contact with each other, resulting in a composite thread having an equilaterally triangular grouping arrangement corresponding to the V shaped groove.

The number of filaments to be arranged into a permanent composite thread, however, is not limitedto three. For example, if six are employed, they may be initially, upon' their introduction below the member, arranged also in triangular configuration, after which successive corresponding portions of the length of each of the filaments will tend to assume the same grouping as they pass beneaththe grouping bar. After withdrawal from the V-groove in the forming or grouping bar, the thread is drawn over the shaperetaining member in a similar groove which holds the individual threads in the same composite grouping relationship while they become adhered to each other.

In practicing the invention to produce generally triangular multifilament threads, a set of V- grooved grouping or forming members is inserted in position in the apparatus. Each forming member is placed in alignment with a group of individual filaments which are brought together member in the groove. The shape-retaining member is provided with V-shaped grooves which alternate with flat or slightly concave upper forming surfaces, and is so adjusted that the V- shaped upper grooves register in alignment with each of the lower V-shaped grooves in the form-' ing bars. The composite thread is thereby held in the proper form as it travels in the upper grooves of the shape-retaining member.

When it is desired to form a multifilament thread having a generally fiat or slightly concave cross-section, a difierent set of grouping bars or produce multi-filament rubber threads of generally triangular cross-section. In Fig. 1, only one side of the apparatus is shown, since the opposite side may be identical therewith. A'tank I open at the top contains a fluid 2, preferably acetic acid or other coagulant for rubber latex.

Groups of nozzles 3, having preferably circular jets, are positioned within the fluid near one end of the tank substantially parallel to the length I of the tank, and are supplied from a latex source (not shown) by pipes 4. Three nozzles are il- .lustrated as emerging from each pipe, although it is obvious that any desirednumber may be supplied, according to the number of filaments desired in each finally formed thread. One latex filament is streamed from each of the nozzles 3.

Each group of filaments 5 is compositely associated by the apparatus into a multifilament composite thread 6 in a manner described hereinafter. At the opposite end of the tank I a roller 1 is mounted above the top of the end wall from the plate I6 to provide means for vertically aligning each group of filaments 5. The pins l2- and 3 are staggered relative to each other, but are generally located along the lines of direction of travel of the filaments. Between the aligning pins and the egress side of the apparatus, grouping or forming bars l5, shown in detail in Fig. 3,

'are horizontally positioned so that each lies along the path of travel..of a filament. Each grouping bar I5 is provided with a central V- shaped groove l6, which may conveniently circumscribe the generally cylindrical bar, or may be formed only in the lower portion of the bar.

' Lateral grooves I! extend parallel to each other partway along each end of the bar to engage pins l6, a pair of which hold each bar IS. A

handle 20, conveniently in the form of a rod whichextends well above the level of the liquid 2,is secured in the top of each bar l5 so that the bar may be lifted out. The pins l8 are mounted within, and extend vertically upward from, an adjustable base 2|. e i

The base 2| has a slot 22 near each end through which a bolt 23 carrying a fiange 26 extends to secure the base 2| adjustably relative to the plate H). The lower end of the bolt 23 is screwed into a-threaded hole toward the end of plate I6, and the base 2| rests slidably on the flange 26, and may be securedin position by the nut 25. A screw-driver slot is provided in the top of the bolt 23 to permit a proper. adjustment of the base 2|, which may be effected by also loosening the nuts at each end of the base, s'oas to change the position of the bolts 23 in the slots 22, whereupon the nuts 25 may be again tightened. This portions of the end frame 21.

to engage the upright A bolt 3| is screwed through a threaded hole 32 at each end of the member 26 and rests on the upper surface of the base of each frame 21. Turning the bolts 3|raises or lowers the member 26 to the desired height relative to the frames 21 and the bottom of the tank I. 7

Longitudinal partition walls 33 are secured by transverse grooved bars 34 to frameworks 35, thereby separating the apparatus into longitudinal channels. i

For the production of generally flat or slightly concave multifilament rubber threads, an alternate set of grouping or forming bars 36 (Fig. 4) is provided with parallel end grooves 31, identical shape-retaining member 26 to the grooves I! in the bars l5, whereby they may be inserted between the pins "3 in lieu of the bars l5. A handle 38 extends from the top of each bar 36 for convenient insertion and withdrawal. I

In operation, latex filaments 5 are streamed from the nozzles 3 into the coagulant bath 2 so that coagulation immediately commences. As each set of filaments 5 passes between the aligning pins 2 and I3, it is vertically aligned into a trio of filaments which passes within the groove l6 under the. grouping or forming bar |5 which arranges the individual component filaments.

in triangular relationship into a composite, lightly adhered thread 40, partially coagulated. From beneath the grouping or forming bars ii, the thread travels within thetriangular groove 26 in the shape-retaining member 26,. which serves to retain the triangular shape of the thread so that efiective adhesion in their par.-

.tially-coagulated condition between the filaments adjustment is desirable in order to align the bars IS in proper relationship with the lineof travel of the filaments 5, after they pass the aligning pins l2 and I3 respectively. 1

. Parallel to the plate l0, and between the plate I!) and the egress end of the tank, a shape-retaining member 26 is supported by generally U- shaped end frames 21 which rest on the bottom of the tank. The shape-retaining member is preferably cylindrical and is provided with V- shaped grooves 28 which alternate with slightly concave grooves 29. The distance between the grooves 28 which are nearest each other is preferably exactly the distance between adjacent grooves IS in the bars I 5. Similarly, the distance between each pair of grooves 29 should be equal to that between adjacenflgrooves i6. It

is not necessary that the grooves 28 and 29 extend'entirely around the member 26, it being sufiicient that they be located only at the top of the member so that a previously grouped thread may be held in proper shape thereby. j

Grooves 30 are provided at each end of the ill ' The ali I a ing or forming member ing, drying and 'for withdrawing forthe V-grooved shape-retaining member 26 is insured. 'From the member 26, the thread travels within the coagulant toward the end of the tank to complete the adhesion of the filaments and to complete coagulation, if desired.

The threads 6 are finally withdrawn from the tank over the roller 7 by suitable means (not shown), whence they may be subjectedto washvulcanizing steps. The means the' threads from the tank may be suitably adjusted so that the speed of the threads on-withdrawal corresponds generally to the rate of speed of formation of the individual filaments. thereby preventing buckling or excessive stretching of the filaments or threads during their manufacture. Depending upon such factors as the rate of When a, generally flat thread is desired, four nozzles 3 may be employed to produce filaments for the thread 42 shown in Fig. 6. A tri-filament generally fiat thread, however,'may be produced by the apparatus described above merely by substituting the slightly concave grouping bars 36 bars I5. and by shifting the 7 I so that the slightly concave surfaces .29 assume the positions previously occupied. by the V- shaped grooves 28.

cut of the filaments below the groupis clearly shown in Fig. 4.

The term, substantially fiat multifilament rubber thread? as employed in this specification .and the appended claims, designates a generally flat'or planarcross-sectional arrangement of the individual filaments in the final composite thread travel of the threads through the tank and the relative densities of present invention provides for the production of a multifilament rubber thread, of which the individual filaments are preferably round in crosssection at the outset, and are not deformed from their original shape at any stage in the process.

It is obvious, of course, that the number and shape of the nozzles 3 emerging from eachpipe 4 may be varied as desired, and that the shape of the grouping surface may correspond to any desired grouping configuration of the filaments.

For example, a rectangular forming surface may be provided in the grouping bar 5, and four or more filaments led therebeneath, resulting in a generally rectangular arrangement of the group of. filaments comprising the composite thread.

The term latex as employed in this specification and the appended claims designates broadly coagulable dispersions of elastic materials including artificial dispersions of rubber or rubberlike materials as well as natural latex, which may be preserved or compounded or otherwise treated as desired, as by vulcanization, and which may be in normal, concentrated, diluted, or purified condition produced by methods wel known in the art.

While certain exemplary methods and apparatus have been shown and described for carrying out the present invention, it is to be understood,

that it may be otherwise embodied within the spirit thereof and within the scope of the appended claims.

Having thus described myinvention, what I claim and desire to protect by Letters Patent is: 1. In the method of producing a multifllament rubber thread, the steps comprising streaming latex through a pluralty of nozzles into a liquid coagulating medium, drawing the filaments thus formed through said liquid medium beneath and in contact with a forming surface within said liquid medium, 'sa'id forming surface being adapted to adhere the plurality of filaments to-.

ether into a thread of the desired grouping configuration, and drawing the thus formed com: posite ,thread. through the liquid coagulating medium.

2. In the method of producing a multifilament rubber thread of generally triangular cross-section, the steps tcomprising streaming latex through a plurality of nozzles into a liquid coagu ating medium, drawing the filaments thus formed throu h said liquid medium beneath and in contact with a forming surface within said li uid medium. said surface having the general shape of an inverted V and being adapted to adhere the plurality of filaments to ether into a enerally triangular thread, and drawing the thus formed composite thread through the liquid coagulating medium. a

3. In the method of producing-a substantially flat multifilament rubber thread, the steps comprising streaming latex througha plurality of nozzles into a liquid coagulating medium, drawformed through said liquid ing the filaments thus in contact with a slightly medium beneath and concave and substan surface within said liquid medium, being'adapted to adhere the plurality of filatially horizontal forming said surface ments laterally into a substantially fiat thread,

and drawing the thus formed composite thread through the liquid coagulating medium.

4. In the method of producing multifllament rubber thread, the steps comprising. streaming latex through a plurality of nozzles into a liquid coagulating medium, drawing the filaments thus formed through said liquid medium beneath and in contact with a forming surface within said liquid medium, said forming surface being adapted to adhere the plurality of filaments together into a thread of the desired cross-sectiona1 configuration, drawing the thus formed composite thread over a shape-retaining member within the liquid coagulating medium.

5. In the method of producing a multifilament rubber thread, the steps comprising streaming latex through a plurality of nozzles into a liquid surface within said medium,

coagulating medium, vertically aligning said filaments thus formed in said liquid medium, drawing the thus aligned filaments through said medium beneath and in contact with a forming said forming surface being adapted to adhere the plurality of filaments together into a thread of the desired grouping configuration, and drawing the thus formed 4 composite thread through the liquidcoagulating medium.

6. In the method of producing a multifilament rubber thread of generally triangular cross-section, the steps comprising streaming latexthrough a plurality of nozzles into a liquid coagulating medium, vertically aligning the filaments thus formed in said liquid medium, drawing the thus-aligned filaments through said medium beneath and in contact with a forming surface, within said medium said forming surface having the general shape oi aninverted V 'and adapted to adhere the'plurality of filaments together into a thread of generally triangular configuration," and drawing the thus formed composite thread. through the liquid coagulating medium.

7. In the method of producing a substantially fiat multifilament rubber thread, the steps comprisingstreaming latex through a plurality of nozzles into a liquid coagulating medium ver-, tically aligning the filaments thus formed in said liquid medium, drawing the thus aligned filaments through said medium beneath and in contact with a slightly concave and substantially horizontal forming surface within said medium, said surface being adapted to adhere the plurality of filaments laterally into a substantially fiat thread, and drawing the thus formed composite thread through the liquid coagulating medium.

8. In the method of producing a multifilament rubber "thread, the steps comprising streaming latexthrough a plurality of nozzles into a liquid coagulating medium, vertically aligning the filaments thus formed in said liquid medium, drawing the thus aligned filaments through said medium beneath and in contact with a lower forming surface within said medium, said, forming surface being adapted to adof filaments together into a grouping such filaments, said grouping means comprising a member having a lower forming surface below the surface of said fluid medium adapted to adheretogether into a thread of the desired grouping configuration a plurality of filaments being drawn through said fluid medium.

10. Apparatus for producing a multifilament rubber thread of generally triangular cross-secadapted to adhere together into a generally tri angular thread a plurality of filaments being drawn through said fluid medium.

11. Apparatus for producing a substantially flat multifilament rubber threadcomprising a tank, a fluid medium within said tank, means for drawing a plurality of at least partially coagulated rubber filaments through said fluid medium, and grouping means intermediate the ends of the tank for grouping such filaments,,said grouping means comprising a member having a slightly concave and substantially horizontal lower forming surface below the surface of said fluid medium adapted to adhere together into a generallyflat thread a plurality of filaments being drawn through said fluid medium.

12. Apparatus for producing a multifilament rubber thread comprising a tank, a fluid medium within said tank, means for drawing a plurality of at least partially coagulated rubber filaments through said fluid medium, grouping means intermediate the ends of the tank for grouping such filaments, said grouping means-comprising a member having a lower forming surface below the surface of said fluid medium adapted to adhere together into a thread of the desired crosssectional configuration a plurality of filaments being drawn through said fluid medium, and

a shape retaining member having an upper surface below the surface of said fiuidmedium' of a configuration corresponding to the conflgura tion of said lower forming surface of said grouping member.

13. Apparatus for producing a multifilament rubber thread comprising a tank, a fluid medium within said tank, means for drawing a plurality of at least partially coagulated rubber filaments through said fluid medium, aligning means for such filaments comprising a plurality of substantialiy vertical bars arranged generally in the line of \travel of such filaments, and grouping means intermediate the ends of the tank for 1 grouping said filaments-said grouping means comprising .a memberhaving alower forming such filaments comprising a plurality of sub stantially vertical bars arranged 'generally in the line of travel of such filaments, and grouping means intermediate the ends of the tank for grouping such filaments, said grouping means.

comprising a member'having a lower inverted- V-shaped surface below the surface of said fluid medium to adhere together into a generally triangular thread a. plurality of filaments being.

drawn through said fluid medium.

15. Apparatus for producing a substantially fiat multifilament rubber thread comprising a tank, a fluid medium within said tank, means for drawing a plurality of at least partially coagulated rubber filaments through said fluid medium, aligning means for such filaments comprising a plurality of substantially vertical bars arranged generally in the line of travel of such filaments, and grouping means intermediate the ends of the tank for grouping such filaments, said grouping means comprising a member having aslightly concave and substantially horizontal lower forming surface below the surface of said fluid medium ad'apted'to adhere-together into a generally flat thread a plurality of filaments being drawnthrough said fluid medium.-

16. Apparatus for producing multifilament rubber threads comprising a tank, a fluid medium within said tank, means for drawing a plurality of at least partially coagulated rubber filaments through said fluid medium, aligning means for such filaments comprising a plurality of substantially vertical bars positioned generally in the line of travel of such filaments,- grouping means intermediate the ends of the tank along such line of travel for grouping such filaments, said grouping means comprising a member having a lower forming surface below the L. DEXTER ALD ICH, 

